Non-volatile Memory Reprogramming via Sub-block Segmentation
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Solution Overview
Problem
Non-volatile semiconductor memory devices face inefficiencies in reprogramming due to the need to erase entire sectors, even for small data updates, leading to energy inefficiency and data degradation from 'disturb' effects on unselected memory cells.
Innovation Solution
A non-volatile semiconductor memory device that uses a control circuit to manage reprogramming operations by initially using smaller sub-block units and switching to sector-level units when a predetermined number of operations is reached, minimizing data degradation and improving energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the entire sector is used as the reprogramming unit, then operational simplicity is improved, but energy efficiency deteriorates when only small data updates are needed
Solution Approach 1:
The memory cell array is divided into multiple sub-blocks, each capable of independent reprogramming. The control circuit identifies and reprograms only the specific sub-block containing the target memory cell, rather than erasing and programming the entire sector. This segmentation enables selective reprogramming, reducing energy consumption while maintaining operational simplicity through automated sub-block identification and control.
2Use of energy by moving object
If smaller reprogramming units are used, then energy efficiency is improved, but data degradation from disturb effects worsens
Solution Approach 1:
The control circuit monitors the number of reprogramming operations performed on each sub-block and maintains a count. When the operation count reaches a predetermined threshold, the control circuit performs a full sector reprogramming to reset the counts and prevent excessive disturb effects. This feedback mechanism dynamically adjusts the reprogramming scope based on operational history, balancing energy efficiency with data integrity protection.
3Adaptability or versatility
If frequent reprogramming is performed for security updates, then security is improved, but data degradation from disturb effects worsens
Solution Approach 1:
The control circuit dynamically adjusts the reprogramming unit size based on the frequency and pattern of reprogramming operations. For frequent small updates, it uses sub-block level reprogramming to minimize energy consumption and disturb effects. When operation counts approach thresholds that could cause data degradation, it automatically expands to sector-level reprogramming to reset all counters. This dynamic adaptation enables frequent security updates while protecting against data degradation through intelligent, condition-based unit selection.
Data Source
AI summary
A control circuit controls a column decoder and a row decoder to perform reprogramming where, before the count of reprogramming operations involving erasures, each targeting one of a plurality of memory cells included in a memory cell array, reaches a predetermined number, a first extent (e.g. a sub-block) including the targeted memory cell and being smaller than the entire extent of the memory cell array is used as the unit of reprogramming, and when the count of reprogramming operations reaches the predetermined number, a second extent (e.g. the memory cell array corresponding to one sector) including the targeted memory cell and being larger than the first extent is used as the unit of reprogramming, and resets the count of reprogramming operations each time it reaches the predetermined number.